means of relays one transmitter may be made to work five hundred receivers. In London a single operator, controlling a keyboard in the central dispatching office, causes typewritten messages to spell themselves out simultaneously in machines distributed all over the metropolis.
The tape machine resembles that just described in many details. The main difference is that it prints on a continuous ribbon instead of on sheets.
Automatic electric printers of some kind or other are to be found in the vestibules of all the principal hotels and clubs of our large cities, and in the offices of bankers, stockbrokers, and newspaper editors. In London alone over 500 million words are printed by the receivers in a year.
HIGH-SPEED TELEGRAPHY.
At certain seasons, or when important political events are taking place, the telegraph service would become congested with news were there not some means of transmitting messages at a much greater speed than is possible by hand signalling. Fifty words a minute is about the limit speed that a good operator can maintain. By means of Wheatstone's automatic transmitter the rate can be increased to 400 words per minute. Paper ribbons are punched in special machines by a number of clerks with a series of holes which by their position indicate a dot or a dash. The ribbons are passed through a special transmitter, over little electric brushes, which make contact through the holes with surfaces connected to the line circuit. At the receiver end the message is printed by a Morse inker.
It has been found possible to send several messages simultaneously over a single line. To effect this a distributer is used to put a number of transmitters at one end of the line in communication with an equal number of receivers at the other end,